Simplify the following expression: $p = \dfrac{r - 5}{6} \div \dfrac{2r}{9}$
Dividing by an expression is the same as multiplying by its inverse. $p = \dfrac{r - 5}{6} \times \dfrac{9}{2r}$ When multiplying fractions, we multiply the numerators and the denominators. $p = \dfrac{ (r - 5) \times 9 } { 6 \times 2r}$ $p = \dfrac{9r - 45}{12r}$ Simplify: $p = \dfrac{3r - 15}{4r}$